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Figure 1. Overview of multiple roles of exosomes in prostate cancer. The previously described roles of prostate cancer exosomes are varied. Many other potential roles demonstrated for exosomes, and/or EV, from other cancer types may also be applicable to prostate cancer exosomes. Cancer exosomes can modulate the immune system. They can transmit tumor antigens to DC, or direct differentiation of myeloid cells towards MDSC/anti-inflammatory (M2) macrophage phenotypes. Exosome-mediated delivery of RNAs can induce endothelial cell proliferation, and exosome-associated proteins can induce endothelial tubule formation. Exosomal-TGFβ can induce differentiation of stromal fibroblasts or MSC towards a pro-angiogenic and tumor supporting myofibroblast-like phenotype. Stromal cell-derived EV can transfer chemoresistance to cancer cells and modulate both cancer cell metastasis and metabolism. Disease progression is further enhanced by cancer exosomes, which have been shown to drive extracellular matrix remodeling and impair osteoclastic differentiation. EV: extracellular vesicles; DC: dendritic cells; MDSC: myeloid-derived suppressor cell; MSC: mesenchymal stem cell; VEGF: vascular endothelial growth factor; MMP: matrix metalloproteinase; FAK: focal adhesion kinase; IGFR: insulin-like growth factor receptor; Src: proto-oncogene tyrosine-protein kinase Src; FGF2: fibroblast growth factor 2; uPA: urokinase-type plasminogen activator; HGF: hepatocyte growth factor, PDGF: platelet-derived growth factor; TGFβ: transforming growth factor beta